1. Field of the Invention
The present invention relates to a speech recognition method which creates frames whose length is predetermined, from sound data obtained by sampling sound, and executes speech recognition processing based on feature components extracted from the respective frames; a speech recognition apparatus adopting the speech recognition method; and a computer program for realizing the speech recognition apparatus, and more particularly relates to a speech recognition method, a speech recognition apparatus and a computer program for removing impulse noise, such as the relay sound of a hazard flasher provided in a vehicle.
2. Description of Related Art
On-vehicle devices, such as a car navigation device, often have a speech recognition function. An on-vehicle device with a speech recognition function has high speech recognition accuracy under an environment where there is stationary noise such as road noise and the engine sound, but does not have sufficient robustness in terms of the recognition accuracy under an environment where there is non-stationary noise that occurs suddenly. In particular, when non-stationary noise occurs during a speech, the recognition rate in this segment is decreased.
As a method for removing non-stationary noise, Japanese Patent Application Laid-Open No. 2003-308092 discloses a method which learns the cycle of non-stationary noise that occurs at a certain cycle in a noise segment, and subtracts a noise power spectrum related to the non-stationary noise from a noise-superimposed voice power spectrum when non-stationary noise is superimposed on a voice segment.